How does tolerance develop?
- By Robert Mauer
- Reviewed by: Dr. Janaka Hanvey, PhD
Tolerance develops when the brain adapts to repeated drug exposure, reducing the drug’s effect over time. As a result, a person may need larger amounts of the substance to achieve the same effect they initially experienced.
This adaptation occurs through changes in receptor sensitivity, neurotransmitter release, and overall brain responsiveness. In some cases, tolerance develops quickly; in others, it builds gradually over longer periods of use.
Tolerance increases risk because higher doses can lead to greater harm, including overdose. It is also one of the pharmacologic criteria used in diagnosing substance use disorders, although it must be interpreted in the context of the overall pattern of use.
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Sources
National Institute on Drug Abuse (NIDA):
https://nida.nih.gov/research-topics/addiction-science
Centers for Disease Control and Prevention (CDC)
https://www.cdc.gov/overdose/prevention/index.html
National Institutes of Health (NIH):
https://www.ncbi.nlm.nih.gov/books/NBK27946/
Substance Abuse and Mental Health Services Administration (SAMHSA):
https://www.samhsa.gov/substance-use